Material of construction for aircraft



C. DORNIER MATERIAL OF CONSTRUCTION FOR AIRCRAFT Filed June 28. 1920 INVENTORI Patented My 6, 1926.

UNITED STATES PATENT OFFICE.

CLAUDIUS' DORNIER, OF FRIEDRIOHSHAFEN, GERMANY, ASSIGNOR TO THE FIRM: LUITBCHIIFBAU ZEPPELIN GESELLSCHAIT MIT IBESCHRANKTER HLI'TUNG, OF

rnmnmonsnnrnn, GERMANY.

' MATERIAL 01 CONSTRUCTION FOR AIRCRAFT.

Application fled June 28, 1920, Serial 1T0. 882,557, and in Germany August 21, 1918.

(GRANTED UNDER THE PROVISIONSDF THE ACT OF MARCH 3, 1921, 41 STAT. 1., 1313.)

Application has also been filed in Germany August 21, 1918.

My invention refers to a novel material especially suitable for air craft on account of its light weight combined with great strength.

Porous metals for the purposes of construction have been-made before now, but in these the porosity itself was the main thing, e. g. in accumulator plates and filter bodies. In contradistinction thereto the invention intends producing a porous material possessing the advantage of a considerably reduced weight attained by the porosity.

Such a porosity can be utilized quite especially in sections, plates and similar structural parts without anydanger in spite of the great strength needed, as the small forces acting upon them require, such small dimensions in width, that ordinary metal cannot be used at all for practical reasons, e. g. in consideration of the knife-like edges and the injuries caused by them.

Especially the use of light metals or high class steel shows that. the thickness of the sheets cannot be reduced to the limit allowing a full utilization of the resistance of the material. The present invention remedies this by supplanting the solid material by the porous one, which, permits using plates of considerably greater thickness due to the highly reduced weight per unit of volume. v The porosity can be obtained by chemical or mechanical means or by a combination of the two.

I may for instance proceed, as described in German patent specification 257490, by heating an alloy to a temperature above the melting point of more readily melting constituents of the alloy, such as the eutectic and then removing the liquefied parts by mechanical means (blowing, pressing, centrifuging and the like) from the solid residue, whereby a metallic body of a densit inferior to rolled sheet metal is obtaine such body presenting a great number of very fine pores. I may, however also employ perforating or punching too of extraorinary fineness allowing to produce closely juxtaposed perforations WhlOh will reduce the weight of a plate thus treated by 25 to 50 per cent without reducin its strength by anything comparable to t e reduction of strength resulting from the punching out of larger holes.

In the drawings a modification of some structural art is illustrated, whose material has t e properties corresponding to the invention. In the drawings- Fig. 1 is a cross-section and Fig. 2 a longitudinal section of a sectional bar of U-section.

The web a and both flanges b of the bar show fine-grained sieve-like perforations. Unperforated are only the transitions (1 from web to flanges and the free ends e of the latter. It is suprosed that the U-bar is to be fastened to ot er structural parts by rivets. In Fig. 2 three rivet holes 7'' are shown. The outlines of the rivet heads are equally shown. As may be gleaned from the rawing, the finerained perforation is no hindrance to so id riveting. For clearness sake the pores and their mutual distances as well as the-rivet holes and the thickness of the plate have been shown lar er than corresponds to actual conditions.

claim:

1. A. structural member for aircraft construction comprising portions made of porous sheet metal.

2. A structural member for aircraft construction comprising portions made of porous light sheet metal.

In testimony'whereof I afiix my signature.

CLAUDIUS DORNIER. 

